Interesting story esp. re the survivor. I've heard this story before, I think the u-boat is in about 100m of water. 7DAYS - Riddle of Nazi U-boat
So at least the much-maligned Bisley achieved something useful! But one question I have is: how would a U-boat have got into the Red Sea? Surely not via the Suez Canal? If they sailed all the way round the Cape, would they have needed one or more rendezvous with supply vessels? Such vessels must have been very vulnerable to discovery by the RN. Some years ago I knew an elderly gentlemen who had been a gunner [DEMS gunner?] on a troopship that was, he told me "torpedoed in the Red Sea". I did ask him the name of the ship, but didn't write it down. His was a rather sad story which I won't go into now, but I often wondered whether his ship had actually hit a mine rather than been torpedoed. At least the account of U533 suggests that it could have been a torpedo - maybe it was U533 that sunk that troopship; the year 1943 would have been correct.
I've been trying to find a thread about a sinking in the Red Sea but have had no luck so far. I know it's here somewhere!